Flexible Display Adhesive Layer Tuning for Impact and Bending
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Solution Overview
Problem
Flexible display devices face issues with reduced lifespan due to excessive bending, damage from repetitive stress, and decreased impact resistance, which can lead to element and wire damage, as well as easy breakage.
Innovation Solution
A display device design incorporating specific adhesive layers with tailored Tan δ values and shear modulus properties, including a lower adhesive layer with Tan δ values of 1.7 to 2.5 and shear modulus of 1 MPa to 5 MPa, along with support members and protection layers, to enhance impact resistance and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the display device is made thinner for bending, then flexibility is improved, but impact resistance is reduced
Solution Approach 1:
The patent employs flexible support members positioned on both sides of the display panel that can bend with the display during folding operations. These support members are thin enough to allow flexibility but provide structural reinforcement to maintain impact resistance. The adhesive layers with specific Tan δ values (1.5-3.0) enable these thin flexible components to maintain structural integrity during bending while providing sufficient mechanical support against impacts.
2Adaptability or versatility
If excessive bending stress is applied to achieve flexibility, then adaptability is improved, but the lifespan is shortened due to element and wire damage
Solution Approach 1:
The patent changes the viscoelastic parameters of the adhesive layers, specifically controlling the Tan δ value (loss tangent) to be between 1.5-3.0 at frequencies of 30,000-100,000 Hz. This parameter optimization allows the adhesive to simultaneously provide flexibility for bending and durability against repetitive stress. The lower adhesive layer has a higher Tan δ value (1.7-2.5) compared to the upper layer, enabling it to effectively dissipate bending energy and protect internal elements and wires from damage while maintaining foldability.
3Loss of energy
If the adhesive layer has high Tan δ value for impact absorption, then energy dissipation is improved, but structural stability may be reduced
Solution Approach 1:
The patent applies different adhesive properties to different locations within the display structure. The lower adhesive layer (between display panel and support member) has a higher Tan δ value (1.7-2.5) for superior impact energy dissipation, while the upper adhesive layer (between display panel and window) has a lower Tan δ value (1.0-2.0) for maintaining structural stability and visual quality. This spatial differentiation of adhesive properties allows the system to simultaneously achieve both impact resistance and structural stability in their respective locations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design improves impact resistance and flexibility, preventing damage and ensuring the display device's longevity by maintaining structural integrity during bending and external impacts.
Implementation Method 1
the lower adhesive layer has a Tan δ value of 1.7 to 2.5 at 30,000 Hz to 100,000 Hz and 25° C.
Implementation Method 2
the lower adhesive layer has a shear modulus value of 1 MPa to 5 MPa at 30,000 Hz to 100,000 Hz and 25° C.
Data Source
AI summary
A display device according to an embodiment includes: a display panel; a window on a side of the display panel; a protection member on another side of the display panel; an upper adhesive layer between the display panel and the window; and a lower adhesive layer between the display panel and the protection member, and the lower adhesive layer has a Tan δ value of 1.7 to 2.5 at 30,000 Hz to 100,000 Hz and 25° C.